Swift Tutorial - Tutorialspoint

Closures in Swift are similar to that of self-contained functions organized as blocks and
called anywhere like C and Objective C languages. Constants and variable references
defined inside the functions are captured and stored in closures. Functions are considered
as special cases of closures and it takes the following three forms:

Global Functions Nested Functions Closure Expressions

Have a name. Do not

capture any values

Have a name. Capture

values from enclosing

function

Unnamed Closures capture

values from the adjacent

blocks

Closure expressions in Swift language follow crisp, optimization, and lightweight syntax
styles which includes.

 Inferring parameter and return value types from context.

 Implicit returns from single-expression closures.

 Shorthand argument names and

 Trailing closure syntax

Syntax

Following is a generic syntax to define closure which accepts parameters and returns a
data type:

{(parameters) -> return type in

statements

}

Following is a simple example:

let studname = { println("Welcome to Swift Closures") }

studname()

When we run the above program using playground, we get the following result:

Welcome to Swift Closures

The following closure accepts two parameters and returns a Bool value:

{(Int, Int) -> Bool in

Statement1

17. SWIFT – CLOSURES...........................................................................................................